Mensa Kakuro : What could be more appealing to Mensa members â or anyone who enjoys a good challenge â than a cunning test of intelligence and logic? That's exactly what these 250 puzzles provide. The trick to kakuro is in making it all add up: the game begins with a grid that looks like a crossword, except that some squares contain small numbers in the corner. Fill in all the empty boxes using the numbers 1 to 9 without repeats so that the sum of each horizontal set of digits equals the number in the black triangle to its left, and the sum of each vertical set of digits equals the number in the triangle above it. The kakuro puzzles start out simple â¦ and get more difficult as the book progresses.